Week 4- Spinal Cord Flashcards by Abbie Baker

What is white matter

Mixture of nerve fibres,neuroglia, blood vessels

Myelinated- white colour

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Name 1st order neuron

Cerebral cortex

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name 2nd order neuron

Internucial neuron in anterior grey column

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Name 3rd order neuron

Motor neurons in anterior grey column of spinal cord

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Describe the structure of the spinal cord

-inner core is grey matter
-H shaped pillar with anterior and posterior columns/horns
-small central canal
-surrounded by outer white matter
-divided into anterior, lateral and posterior white columns

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What is grey matter proportional to

The amount of muscle innervated at that level

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Where is grey matter largest

Cervical and lumbosacral region

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What does grey matter consist of

Nerve cells
Neuroglia
Blood vessels

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Where is the cervical enlargement

4th C- 2T

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Where is limbo-sacral enlargement

2 L- 3S cord segment

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How many spinal nerves are attached to spinal cord

31 pairs

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What are spinal nerves attatched to

Anterior/ ventral (motor roots)

Posterior/dorsal (sensory roots)

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what does each spinal posterior nerve possess

Posterior root GANGLION

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What are ganglia

Clusters of nerve cell bodies that carry nerve signals to and from CNS

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What are sensory ganglia

Ovoid shape with an oval cell body

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What are motor ganglia

They form a long chain in the spine from the base of skull to tail.
Irregular shaped cell bodies

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What do anterior + posterior Ramus have

Sensory fibres and motor fibres

s anterior or posterior ramus larger

Anterior= larger
Posterior= smaller

What is the cauda equina

Collection of nerves at the end of spinal cord

What is the size of cervical and thoracic canal

Cervical= large
T= small

Describe problems with paraplegic

Limited mobility
Chronic pain
Reduced bowel and bladder function
Loss of sexual function
Loss of muscle tone in legs
Weight gain

What level is quadriplegic paralysis

Cervical

Name problems with quadriplegic

-Limited / complete absence of arm/hand function
-Problems speaking, swallowing or breathing without assistance
-difficulty performing daily tasks, dressing, eating
-muscle tone loss
-loss of bone density

List levels of spinal cord injury

A= complete injury. No function or sensation at the end of the cord

B=sensory incomplete. Sensory but not motor function retained

C=motor incomplete. Motor function is present to the end of spinal cord.

D= muscle function below level of injury is against gravity

E= normal

What cells control spinal cord function

Long axons Sensory neurons Spinal interneurons

Describe how long axons assist in spinal cord function

Control skeletal muscles in neck torso and limbs called motor neurons

Describe how sensory neurons assist in spinal cord function

Dorsal root ganglia cells/ afferent cary info from bidy to spinal cord. Found outside spinal cord

Describe how spinal interneurons assist in spinal cord function

Cells that help integrate sensory info with generate coordinated signals that control muscles, lie within spinal cord

Describe myelin

-white fatty substance produced by Schwann cells -outer nerves coated with myelin (white matter) -inner spinal cord nerves not coated with myelin (grey matter)

Describe peripheral nerves

Cranial and spinal nerves Consist of parallel bundles of fibres that may be efferent of afferent axons Surrounded by ct sheaths

Define reflex

Involuntary response to stimulus

What does a reflex arc consist of

Receptor organ Afferent neuron Control centre Efferent neuron Effector organ

What can reflexes be used to test

Any abnormalities in sensory pathways (CNS, PNS) Lesions in reflex arc and level of lesion Absent reflex and sensory loss- afferent arc of reflex Absent reflex with paralysis - efferent arc

Describe stretch reflex

Monosynaptic Most rapid Simple reflex arc with a single synapse between afferent and efferent neuron Example- patella reflex. Muscle spindles

Describe flexor withdrawal

Autonomic response, withdrawing a limb from a painful stimulus Intensity of reflex proportionate to intensity of stimulus Polysynaptic reflex- uses interneurons Passes signals from sensory to motor neurons- creating multiple synaptic connections

Describe the process of flexor reflex

-step on stimulus -fibres send signal to spinal cord -interneurons branch to different spinal cord segments -motor figures in several segments are activated -more than 1 muscle group activated to lift foot off stimulus

Describe babinski reflexes

PLANATR REFLEX- (tool put under foot middle). Curling of toes is healthy in adults Babinski sign (positive babinski reflex) occurs in absence of descending inhibition. It is normal in infants, but pathological in adults

Name 2 arteries that supply blood to the spinal cord

Anterior and posterior spinal arteries

Why is the circle of Willis circle shaped

Avoid blockages to supply the brain of bloody. Other ways to allow blood to enter

Function of circle of Willis

Provide blood flow between A and P circulations of the brain protecting against ischemia in the event of vessel disease or damage in one or more areas.

Name arteries that form circle of Willis

Posterior communicating artery Anterior cerebral artery Anterior communicating artery Posterior cerebral artery